Microtubules and associated molecular motors are responsible for multiple cellular motion. One of the requirements to properly achieve these functions is correct assembly of microtubule-associated molecules, particularly the mechanochemical motors. For example, the binding of cytoplasmic dynein to kinetochores contribute to chromosome segregation during cell division. The other striking example is that 4 isoforms of dynein must be targeted to the correct location to achieve highly regulated ciliary/flagellar motility, which is critical for the function of sperm and epithelium in oviduct and respiratory tract. The failure of precise targeting of dynein could potentially be translated into cancer, infertility, respiratory dysfunction or sensory impairment. However, little is yet known about the molecular mechanism which direct motors to the correct position in the cell. This project is to study the targeting mechanism of inner dynein arms to specific sites on Chlamydomonas flagellar microtubules. Our approaches include: 1) Characterize the functional domain of inner dynein arm, Il responsible for targeted assembly by studying the rebinding of inner arm dynein Il and its subunits to axoneme lacking Il in vitro. 2) Antibodies against II intermediate chains will be raised to identify the location and assembly polarity of Il. 3) Identify the proteins involved in the docking site for II binding using chemical cross linker and antibodies. 4) The cDNA of the intermediate chain of Il will be cloned and sequenced to facilitate further study the molecular mechanism of targeted assembly.